1. Field
The present disclosure relates generally to ultrasonic inspection and, in particular, to a method and apparatus for identifying undesirable conditions in an object using ultrasonic inspection. Still more particularly, the present disclosure relates to a method and apparatus for ultrasonic inspection using signals with an incidence angle.
2. Background
Aircraft are being designed and manufactured with greater and greater percentages of composite materials. Some aircraft may have more than fifty percent of its primary structure made from composite materials. Composite materials may be used in aircraft to decrease the weight of the aircraft. This decreased weight may improve payload capacities and fuel efficiencies. Further, composite materials may provide longer service life for various components in an aircraft.
Composite materials may be tough, light-weight materials created by combining two or more dissimilar components. For example, a composite may include fibers and resins. The fibers and resins may be combined to form a cured composite material.
In particular, key components, such as wings and fuselage skins, may be constructed with composite materials such as, without limitation, a composite laminate. With more and more critical structures being made of composite laminates, methods and techniques to assure that these components meet quality standards are needed more than ever before.
The presence of foreign materials or debris within a composite component is an example of a known undesirable condition that may occur during processing to create composite components. Currently, much time, effort, and money may be spent on non-destructive measurement systems designed to detect and quantify the debris in composite components, such as those made using carbon laminates. Other examples of undesirable conditions include, for example, porosity within the component and delamination.
Ultrasonic testing involves sending ultrasonic pulse waves into an object to detect undesirable conditions or to characterize materials. In ultrasonic testing, one or more ultrasound transducers are passed over an object that is being inspected. The transducers are typically separated from the test object by a coupling material. This coupling material may be, for example, a liquid such as oil or water. The coupling material is used to prevent signal loss. In this manner, undesirable conditions may be detected.
However, identification of debris may be difficult using one transducer for ultrasonic testing. Further, ultrasonic inspection using more than one ultrasound transducer may be undesirably difficult to control or implement.
Therefore, it would be desirable to have a method and apparatus that take into account at least some of the issues discussed above, as well as other possible issues.